Toughness and ductility improvement of heavy EH47 plate with grain refinement through inter-pass cooling

Wu, Jian; Wang, B.; Misra, R.D.K.; Wang, Z.D.

doi:10.1016/j.msea.2018.07.001

Cited by 36 publications

(10 citation statements)

References 32 publications

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“…Under conventional heat input conditions, relatively coarse prior austenite grain boundaries (PAGBs) were generated, and the bainitic laths were distributed in different directions in the prior austenite grains, together with long and parallel M-A constituents. The coarse bainite located in the CGHAZ area had a large crystallographic effective size, which increased the linear propagation path of the cleavage cracks, and undoubtedly impaired the fracture toughness [ 20 , 21 ]. At the same time, no plastic deformation occurred at the fatigue crack tips, and the major crack extended along the coarse PAGBs [ 22 ].…”

Section: Resultsmentioning

confidence: 99%

Comparison of Fracture Toughness in the Coarse-Grain Heat-Affected Zone of X80 Pipelines Girth-Welded under Conventional and Ultra-Low Heat Input

Liu

et al. 2022

Materials

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The coarse-grain heat-affected zones (CGHAZs) of X80 girth-welded steel pipelines are prone to embrittlement, which has an extremely adverse effect on their structural integrity. In the present work, the fracture behavior of the CGHAZs of X80 girth welds under the conditions of conventional and ultra-low heat input was studied. The fracture toughness of CGHAZs was evaluated using the crack tip opening displacement (CTOD) test at −10 °C, and the fracture behavior mechanism of CGHAZs were clarified by analyzing microstructural characteristics at prefabricated fatigue cracks containing fracture cloud image, scanning electron microscopy (SEM), and electron back-scatter diffraction (EBSD) figures. The results illustrate that the average fracture toughness (CTOD) value of the ultra-low heat input CGHAZ is 0.6 mm, and the dispersion of CTOD values is small, while the CTOD value of conventional heat input is only 0.04 mm. The ultra-low heat input makes the high-temperature residence time of the coarse-grained region short, reduces the proportion of prior austenite grain boundaries, and inhibits the formation of strip-like bainite and island-like M-A components. The reduction of these deleterious ductile microstructures increases the plastic reserve and deformation capacity of the CGHAZ.

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Section: Resultsmentioning

confidence: 99%

Comparison of Fracture Toughness in the Coarse-Grain Heat-Affected Zone of X80 Pipelines Girth-Welded under Conventional and Ultra-Low Heat Input

Liu

et al. 2022

Materials

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“…This can be attributed to that with the increase of cooling speed, only partial ferrite transformation occurred during the cooling process. In addition, since they were cooled to a lower temperature range, the ferrite and pearlite transformations were inhibited, while the amount of bainite microstructure at medium and low temperatures increased gradually [12,13]. The microstructure at the 1/2-thickness, where the cooling rate was slower, consisted mostly of polygonal ferrite and pearlite.…”

Section: Microstructural Evolution Analysismentioning

confidence: 99%

Effect of Roller Quenching on Microstructure and Properties of 300 mm Thickness Ultra-Heavy Steel Plate

Han

Wang

et al. 2020

Metals

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In this paper, a 300 mm thickness ultra-heavy steel plate was selected as the research object. In addition, special roller quenching equipment and a new testing method were used to measure the quenching temperature curve at different positions of the steel plate. The relationships and corresponding interaction mechanisms between cooling rate, microstructure, and mechanical properties of an ultra-heavy steel plate during roller quenching were investigated. The results indicated that the cooling rate, strength, hardness, and impact energy decreased gradually along the thickness direction of the plate, while the cooling rate, average grain size, and mechanical properties were relatively uniform with little change along the length direction of the plate. The experimental results provide an effective way to further control the microstructure and properties of ultra-heavy steel plates during roller quenching.

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“…Wu et al [ 7 ] used the interpass cooling technology during rough rolling, achieving 51.7% HAGB and mixed microstructures of acicular ferrite (AF), polygonal ferrite (PF), quasipolygonal ferrite (QF), and a low amount of granular bainite in EH47 steel with a thickness of 60 mm. In a work by Shen et al, [ 8 ] 70% HAGBs and homogeneous ferrite microstructures through the thickness with ferrite volume fraction of 82.4% and grain size refined to 6.7 μm at one‐fourth thickness of the 40 mm heavy plate were obtained by optimizing the rolling reduction distribution at the nonrecrystallization region of austenite with the total rolling reduction ratio of 4.…”

Section: Introductionmentioning

confidence: 99%

A Two‐Step Thermomechanical Process for Improving High‐Angle Grain Boundary Proportion and Achieving Delamination Toughening in Hot‐Rolled Steel with a Limited Slab‐to‐Plate Ratio

Wang

Tian

et al. 2022

steel research int.

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A two-step thermomechanical process is utilized to increase high-angle grain boundary (HAGB) proportion and achieve delamination cracks in hot-rolled steel produced by a limited slab-to-plate ratio. Three plates are austenitized at 900 °C and hot rolled with 65%, 57%, and 50% reduction at 880-800 °C after rolling at 1100-1050 °C followed by water cooling. Water quenching tests are carried out to prove the advantages of the two-step thermomechanical process. The steels having 69.9-71.8% HAGB proportion and delamination cracks are fabricated with a final thickness of 48 mm and a total rolling reduction ratio of 3.33. The high HAGB proportion is attributed to the abnormally refined prior austenite grain of 18.5 AE 10.5 μm caused by the heating temperature of 900 °C. Thus, 93-129% more effective interfacial area (193-229 mm À1 ) can be provided than the conventional process (100 mm À1 ) during rolling below the nonrecrystallization temperature of austenite. Abundant ferrite grains that form and impinge from the different prior austenite grains obtain 33.6-34.5% frequency distribution of the grain boundary misorientation angles, which fall into 20°-47°. The premises of delamination toughening are that the delamination cracks appear at the opposite side of the V-notch with a reduced number.

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Toughness and ductility improvement of heavy EH47 plate with grain refinement through inter-pass cooling

Cited by 36 publications

References 32 publications

Comparison of Fracture Toughness in the Coarse-Grain Heat-Affected Zone of X80 Pipelines Girth-Welded under Conventional and Ultra-Low Heat Input

Comparison of Fracture Toughness in the Coarse-Grain Heat-Affected Zone of X80 Pipelines Girth-Welded under Conventional and Ultra-Low Heat Input

Effect of Roller Quenching on Microstructure and Properties of 300 mm Thickness Ultra-Heavy Steel Plate

A Two‐Step Thermomechanical Process for Improving High‐Angle Grain Boundary Proportion and Achieving Delamination Toughening in Hot‐Rolled Steel with a Limited Slab‐to‐Plate Ratio

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